Maria Sharapova's fearsome form continued on Sunday when she claimed an enviable record on the way to the Australian Open quarter-finals.

With her victory over Belgian Kirsten Flipkens, the Russian set a new mark of the fewest games conceded in the first four rounds of the Open since 1988 when the 128-person draw was introduced.

Sharapova has dropped just five games in her four matches at Melbourne Park, beating the record of eight held by Steffi Graf (1988) and Monica Seles (1991 and 1993).

The overall grand slam record is held by French player Mary Pierce, who lost four games on her way to the French Open quarters in 1994.

''I'm certainly happy to be playing this well, but it only gets tougher from here,'' Sharapova said.

Despite the ease of her progress, Sharapova is cautious heading into the second week.

''It's really about keeping your focus, no matter what the score is, no matter if you're up,'' she said. ''I didn't start the match really great. I was facing a different type of opponent today and I was making a few more mistakes than I would have liked in the beginning.

''It's always much easier said than done to keep that focus, especially when you have a first set. All of a sudden - especially in women's tennis - things can change really quickly. It's about sticking to your game plan, being consistent, but playing your game.''

She now meets compatriot Ekaterina Makarova, who outlasted German Angelique Kerber 7-5, 6-4.

Last year, the 24-year-old from Moscow knocked out Serena Williams in the same round and is looking forward to her match-up with Sharapova.

Kerber, the fifth seed, had won the past three meetings between the pair but struggled on Sunday and was intermittently treated for a back problem. She said the injury had developed recently.

''I will go after here to the physios and to the doctor, and then I will see what's going on there,'' Kerber said.

Makarova said she wanted to play Sharapova because she had improved since her quarter-final appearance here last year. ''I played against her a lot last year and I think it would be really interesting,'' Makarova said. ''I am more prepared this time.

''Last year I was surprised a little bit and had so many thoughts in my mind.''